Method writeFrame

src/ws-framing.ts:93–127

(opcode: number, payload: Buffer)

  }

  private writeFrame(opcode: number, payload: Buffer): void {
    if (this.socket.destroyed) return;

    // Server-to-client frames are NOT masked (per RFC 6455 §5.1)
    const length = payload.length;
    let header: Buffer;

    if (length < 126) {
      header = Buffer.alloc(2);
      header[0] = 0x80 | opcode; // FIN + opcode
      header[1] = length;
    } else if (length < 65536) {
      header = Buffer.alloc(4);
      header[0] = 0x80 | opcode;
      header[1] = 126;
      header.writeUInt16BE(length, 2);
    } else {
      header = Buffer.alloc(10);
      header[0] = 0x80 | opcode;
      header[1] = 127;
      header.writeUInt32BE(0, 2);
      header.writeUInt32BE(length, 6);
    }

    try {
      this.socket.write(Buffer.concat([header, payload]));
    } catch (err: unknown) {
      // Expected when socket is destroyed between our check and write.
      // Log unexpected errors so they don't vanish silently.
      if (!this.socket.destroyed) {
        const msg = err instanceof Error ? err.message : String(err);
        console.error(`[LLMock] Unexpected writeFrame error: ${msg}`);
      }
    }
  }

  private parseFrames(): void {
    while (this.buffer.length >= 2 && !this.closed) {